1. Field of the Invention
The present invention related generally to spinners for gas turbine engine fan assemblies and, more specifically, to such one piece spinners and to such spinners for fan assemblies having fan blades with circular arc dovetail roots that mate in circular arc dovetail slots in a disk of a fan rotor.
2. Discussion of the Background Art
A turbofan gas turbine engine used for powering an aircraft in flight includes a fan assembly having a plurality of circumferentially spaced apart fan blades extending radially outwardly from a rotor disk. Ambient airflow is channeled between the blades and pressurized thereby for generating thrust for powering the aircraft in flight. The fan assembly typically includes a plurality of circumferentially spaced apart fan blades each having a dovetail root disposed in a complementary, axially extending dovetail groove or slot in a perimeter or rim of a rotor disk. The dovetail grooves are defined by dovetail posts and are complementary in configuration with the blade dovetail roots for radially retaining the blades to the rotor disk. The blades are also axially retained in the rotor disk to prevent axial movement of the blades in the upstream and downstream directions. A spinner is mounted to a front end of the fan assembly to provide smooth airflow into the fan. It is highly desirable to have a one piece spinner.
Some conventional gas turbine engines have one piece spinners that attach directly to the disk post. Other conventional gas turbine engines have two piece spinners that have an upper portion of the spinner attached to a flange extending axially forwardly from the disk and a lower portion of the spinner attached to the upper portion of the spinner. This arrangement provides access to the bolted joint between the upper spinner and the disk flange when the lower portion removed. The lower portion of the spinner is attached after the joint is secure.
Besides a one piece spinner being desirable for structural and cost reasons, it is desirable to accommodate the circular geometry of the dovetail which makes attaching the spinner directly to the disk post difficult, if not, impossible. It is also desirable to have a spinner that incorporates features to help provide a low radius hub design which incorporates a circular arc dovetail root and slot.
An exemplary embodiment of the invention is a spinner for mounting to a front end of a fan assembly of a gas turbine engine. The spinner includes a single piece substantially conically shaped hollow body that is circumscribed about a centerline which extends aftwardly from a tip to an axially aft spinner end. A plurality of bolt holes extend axially parallel to the centerline through the hollow body at an axial location between the tip and the aft spinner end. In a more particular embodiment, the hollow body includes a forward conical section extending aftwardly from the tip to a transition section, an aft conical section extending aftwardly from the transition section to the aft spinner end, and the bolt holes are axially located in the transition section. An aft spinner flange is attached to the axially aft spinner end, a plurality of flange lightening holes are axially disposed through the aft spinner flange, and the flange lightening holes are circumferentially distributed around the aft spinner flange. A plurality of bosses circumferentially are distributed around an inner surface of the hollow body at the axial location. A boss counterbore co-axial with and axially adjacent to and forward of each of the bolt holes extends axially parallel to the centerline through the hollow body and each of the bosses.
Another embodiment of the invention is a gas turbine engine rotor disk assembly in which the spinner is attached to a disk of the assembly. The assembly includes a number of annular hubs circumscribed about a centerline, wherein each of the hubs connected to a disk rim by a web. A plurality of circumferentially spaced apart dovetail slots are disposed through the rim, extending circumferentially between disk posts, extending axially from a forward end to an aft end of the rim, and extending radially inwardly from a disk outer surface of the rim. An annular forward extension having an annular forward flange and connected to an annular forward arm extends forwardly from a forward most one of the webs. The spinner is connected to the forward extension by spinner bolts disposed through the bolt holes and forward bolt holes in the annular forward flange. A plurality of fan blades having dovetail roots are disposed in the dovetail slots and non-integral gas turbine engine fan blade platforms are mounted on the disk and circumferentially disposed between the fan blades. The platforms include platform walls with radially outer surfaces facing radially outwardly and radially inner surfaces facing radially inwardly. Forward mounting lugs depend radially inwardly from the platform walls at forward ends of the platform walls and aftwardly extending platform pins are secured to corresponding ones of the forward mounting lugs. Post holes extend axially aftwardly into a circular rim surface of the rim and the platform pins are disposed in corresponding ones of the post holes. An aft spinner flange attached to the axially aft spinner end and the forward mounting lugs of the platforms are trapped between the forward facing circular rim surface of the rim and the aft spinner flange. Each of the platform pins has an aftwardly extending smooth cylindrical body attached to a narrower shank, the smooth cylindrical body is disposed in the post holes, and the shank has a threaded free end. Internally threaded nuts are screwed onto the free ends securing the platform pins to the forward mounting lugs. A plurality of flange lightening holes are axially disposed through the aft spinner flange and are circumferentially distributed around the aft spinner flange. The internally threaded nut are disposed through at least some of the lightening holes. Each of the post holes extend into a corresponding one of the posts.